As I recall, the default glob is unnecessarily slow on Win32 because it does stat a lot more than it needs to. And stat is unnecessarily slow on Win32 because it does some expensive things in order to fill in bits that are rarely used. If doing glob to a remote network share (at least), the slow-down can be quite dramatic (orders of magnitude).
I had an idea for using something like an environment variable to allow skipping the expensive parts of stat but I don't have it "swapped in" at the moment. But the over-use of stat by the default glob should just be fixed.